Encrypt the Data in the Database for Specific Employees

I've used the functions encrypt() and decrypt() for the data to be accessible in PIA for specific employees taking their user ID as a criteria. But I should encrypt the data for same employees in the back end as well. Please give the solutions.

You can use the Oracle Data Integrator (ODI) to mask the data value (means
that you convert / scrable / change the data value) on a field of same data
type and same length to a imaginary data value. We did implement this for
our Non production environments. Using the ODI would permananetly mask the
data value and all the processing and transactions will have to be done
with those values.

As far the front end PIA is concerned for production environments we did use
the Query and Data Security configurations and setup to allow data to be
viewed by end users. You can implement Query Security and Data Security
combined with Peoplesoft Roles and Permission lists which will allow the
users to view the data that they are authorized to view.

But before we sink our hands into encryption , am just thinking how will it
impact the related information ?

(1) what is the scope of this encryption ? Means which tables ?
(2) will it pose problems when you join tables in psquery of encrypted and
non-encrypted ?
(3) possible turn around time lags due to encrypt /decrypt ?
(4) is there an app package class for decrypt ?

well...you need to elaborate the use here. you cannot decrypt password and that is a period however credit card encryption and decryption is the most popular business process for encryption/decryption.
find my answers in blue.

(1) what is the scope of this encryption ? Means which tables ? as far as I know there are no tables for storing this encryption information.
(2) will it pose problems when you join tables in psquery of encrypted and
non-encrypted ? no tables, so no queries.
(3) possible turn around time lags due to encrypt /decrypt ?
you need to elaborate this.
(4) is there an app package class for decrypt ?
SCM_UTILITES:Encryption:PSCipher method decodepassword

As I understand from the original posting I think Abhilash is looking for a
solution to encrypt the data in the "back end". If the data in the back end
has to be permanently encrypted, then as I quoted earlier, implementation of
ODI can help. If any user who needs to see this encrypted information then
appropriate code need to developed.

Yes, what pstechfunc has said in last comment is correct. Let me be more clear.

I've developed a tool for data masking, user of this tool can specify which field in which record has to be masked and for whom. and he has to run a process. That process encrypts that data in the database. It is general. Whoever goes and see the data, it'll be masked.

In PIA (front-end), users whose IDs are specified in the tool will see the encrypted data only. Users whose IDs are not specified, they'll see the decrypted data. I've used decrypt() function here.

Now, the requirement is, even in back-end it has to happen as it is in front-end. The user IDs which are specified in the tool, should see the masked data in back-end and all other users should see the original data. How to achieve this ?

Thanks everyone for your replies and interest. Looking forward for more replies as I've told the case clearly now.